Inspecting or sorting apparatus



May 28, 1963 l.. K. PARKER INSPECTING OR SORTING APPARATUS 7 Sheets-Sheet 2 Filed Sept. 24, 1959 M .w m w, ma n I n .n u S. .Vm Dm. .Qw Q u, v s DL Q A .u .m .mi Qmmmwww Qmmgm .umwMuM mmwq NE* ckmwwm um@ SQW mwQ m SQ. w WQ @umm .UGQm wGxQ Q A T AH w mf@ A l 4 t Q u .N

May 28, 1963 L. K. PARKER 3,091,332

INSPECTING OR SORTING APPARATUS File'd Sept. 24, 1959 7 Sheets-Sheet 5 PULSE HE/GH 7 PULS E D/SCR. TR/G. STRETCHER GATE SELECT/VE DEZ SLCER HOLE INSPECTION AMP HEAD Inventor Legna kmh RLY/@Y B ma A Harney May 28 1963 K. PARKER 3,091,332

INSPECTING OR SORTING APPARATUS Filed Sept. 24, 1959 7 Sheets-Sheet 4 Inventor Leih-e. Kean/'hm PLYkeY B man? s, MMM

Attorney May 28, 1963 l.. K. PARKER 3,091,332

NsPEcTING 0R soRTING APPARATUS Filed Sept. 24, 1959 7 Sheets-Sheet 5 Inventor Le'gl (e. Kem/Tom Poor e-r B RAMA-313m@ Attorney May 28, 1963 l.. K. PARKER 3,091,332

INSPECTING OR SORTING APPARATUS Filed Sept. 24, 1959 '7 Sheets-Sheet 6 Inventor Les fe keanflbm Pw 'Key 'vvv' Il Il A vvv' AVA'A'AvA l /1 Harney May 28, 1963 L. K. PARKER 3,091,332

INSPECTING OR SORTING APPARATUS Filed Sept. 24, 1959 7 Sheets-Sheet 7 Inventor Lesbe Kem/127, Ew key A Harney vaperture crosses the said axis.

3,991,332. INSPEC'IING 0R SRTING APPARATUS Leslie Kearton Parker, Lynwood, England, assigner to Aluminium Laboratories Limited, Montreal, Quebec,

Canada Filed Sept. 2.4, 1959, Ser. No. 842,134 Claims priority, application Great Britain Sept. 25, 1958 15 Claims. (Cl. 209-75) This invention relates to apparatus for inspecting or sorting karticles and particularly .to apparatus of the kind in which .articles are moved in succession past one or more inspecting stations and defective articles are removed from the normal ones by automatic means.

According to one aspect, the invention consists in apparatus for testing metal articles for defects in their periphery which com-prises two pick-up coils mounted so as to lie symmetrically about opposite sides of a normal sized article as it is passed between them, means for generating a magnetic eld in the vicinity of the parts of the article adjacent each coil, and means lfor comparing the voltage induced in the two coils. Conveniently the two pick-up coils are arranged in a bridge circuit which will become unbalanced if owing to a defect in the article the voltages induced in the two coils are unequal, and this unbalance may be caused to generate a signal which is effective to -operate means for removing the article.

This test may be used not only to eliminate articles having dimensions which are below standard, assuming in such case that the article will no longer be symmetrically disposed between the two pick-up coils, but also to eliminate articles which are of standard dimensions but in which the metal is defective, for example is blistered or laminated.

According to another aspect of the invention, apparatus for testing metal articles as regards the presence and uniformity of an aperture intended to be formed therethrough comprises two spaced coils between which the article to be tested is passed so that the aperture passes across an axis extending between the two coils, means yfor energising one of the coils with alternating current and means for measuring the voltage induced in the other coil as the Conveniently the voltage in this coil may be compared with a standard voltage and any differences used to generate a signal which actuates means for removing the article. lFor this purpose the standard voltage may be produced by positioning another article which has an aperture of standard dimensions between a similar pair of coils one of which is also energised with alternating current, and the two coils in which voltages are induced may be connected in a bridge circuit which if it becomes unbalanced may be used to generate a signal.

The apparatus of this invention may also include means for inspecting the articles as regards uniformity of their maximum dimension in a direction at right angles to their direction of movement which comprises a shaft or roller which is adapted to be rotated and which is positioned with its axis of rotation above and parallel with the direction of movement such that an article of standard dimensions will just not make contact with the periphery of the shaft or roller, whereas any increase in the dimensions or any projections on its upper surface which extend beyond the prescribed dimensions will Contact the shaft or roller which will cause the articles to be rejected.

While the invention may be used for inspecting articles which are moved by any suitable means, for example a conveyor, in succession past the inspecting station or stations, it is particularly suitable for use in inspecting articles which are of circular shape in cross-section and which accordingly can be moved by causing them to roll along a runway. In such case the pick-up coils used lfor testing ice the articles as regards defects in their periphery may be extended in the direction of movement of the articles so that their length is at least equal to half the circumference, whereby the whole of the circumference will be examined rfor defects as the articles roll by the coil-s. Likewise the length of the rotatable shaft or roller should be made at lleast Iequal to one half of the circumference of the articles.

Where the apparatus of this invention is used to inspect disc-like articles which are non-synunegtnical or nonplanar, for example the articles may have an annular ange or may be of concavo-convex shape, it is normally preferred that the articles shall all have the same orientat-ion as they pass the testing stations and the invention further includes means which permit articles of one orientation to pass freely down a runway and which removes articles of the other orientation from the runway, inverte them, and then returns them to the runway.

In order that the invention may be clearly understood one form thereof will now be described with reference to an apparatus specifically designed for testing circular metal discs or slugs having a central hole and which are formed from aluminium sheet by a stamping operation. Such slugs are used subsequently in an extrusion process in the manufacture of aluminium articles and it is important that they shall beof uniform dimensions and quality. As manufactured these slugs may suffer from any of the following defects:

(l) Lenticular defects, that is to` say the slugs have small pieces bitten out of their periphery;

(2) Protrusions at the periphery due to damage;

(3) Blisters on the periphery;

(4) Laminations in a direction normal to the axis;

(5) Wrong diameter `due to accidental mixing of slugs of diiferent diameters;

(6) The centre hole not through-punched or not punched at all, and

(7) The centre hole wrong size due to accidental mixing of slugs having different hole sizes.

The apparatus now to be described is specifically designed to reject slugs having any of the above defects.

In the accompanying drawings:

FIGURE l shows diagrammatically the sequence of operations of the apparatus,

FIGURE 2 is a block diagram of the electrical apparatus used at one inspection station,

FIGURE 3 is a diagram of part of the electrical apparatus at another inspection station,

FIGURE 4 is a block diagram of the electrical apparatus used at that station,

FIGURE 5 is a fragmentary plan of a feed bowl showing means for rejecting slugs having gross defects,

FIGURE 6 is a .side elevation and FIGURES 7a and 7b are a cross-section of an orienting chute',

FIGURE 8 is a diagrammatic side elevation of an escapement,

FIGURE 9 is a diagrammatic side elevation of a means for rejecting over-sized slugs,

FIGURE 10 is a diagrammatic view of part of the inspection station shown in FIGURE 2,

FIGURE ll is a Wiring diagram of electronic apparatus for use in the inspection station shown in FIGURE 2,

FIGURE l2 is a diagrammatic View of part of the inspection station shown in FIGURE 4, and

FIGURE 13 is a wiring diagram of the electronic apparatus at the inspection station shown in FIGURE 4.

Referring to the drawings, FIGURE 1 shows the general arrangement of the apparatus and the order of the various inspecting stations which will be described in detail below.

The slugs to be examined are supplied to a Vibration bowl 1 which in known manner feeds the slugs one by one up an inclined path round the periphery of the bowl and to the top of an inclined runway down which the slugs roll past the various inspecting stations.

In order that slugs having gross lenticular defects are eliminated as soon as possible, the bowl is arranged, as shown in FIGURE 5, in such a way that in their passage up the inclined path '2S to the outlet the slugs 29 pass over a grid formed by the two bars 3i) and 31 which are so dimensioned and disposed that only substantially complete slugs can pass the grid successfully, while slugs having gross defects, such as slug 32, will overbalance and drop through the grid and into a rejection chute 33 at the side of the bowl 34.

Shortly after leaving the bowl the runway is formed with a gap 2 (FIGURE l) over which normal slugs, having acquired suiiicient velocity in their passage down the runway, will jump. Slugs having large lenticular defects, however, will not roll satisfactorily and will therefore not acquire suicient velocity to jump the gap, and will accordingly fall through the gap into a rejection chute.

Since the apparatus is designed also for inspecting slugs which are of domed or concave-convex shape and it is desired that all the slugs shall have the same orientation when they pass the further inspecting stations, the slugs are now passed into an orienting chute 3 (FIGURE l) which sorts the slugs according to their orientation and inverts those slugs having one particular orientation. As shown in FIGURES 6 and 7, the runway 36 at this point has one wall 37 which is inclined away from the vertical so that the slugs lean against it as they pass, and between the runway and this wall is provided a rollway inclined with respect to the runway. 'I his rollway may be in the form of a slightly projecting wedge-shaped section which constitutes a gradually ascending narrow ledge 3S. lIf a domed slug 39 going down the runway has its concave surface toward the wall, the perimeter of this concave surface will bear against the wall 37 (FIGURE 7a). This slug will run up this ledge 33 and will enter a secondary runway consisting of a rectangular shaped chute 40 which is twisted through ,an angle of 180 about an axis parallel to its length and then joins the main runway. Slugs passing through this chute are therefore turned through 180 and then re-enter the main runway. Domed slugs 41 which have their convex face disposed toward and bearing against the wall 37 of the chute (FIGURE 7b) will, however, not engage the ledge 38 when they encounter it and will continue down the main runway.

Following the orienting chute is an escapement 4 (FIG- URE 1) which is arranged to release the slugs one by one so that they pass individually through the following inspection stations. As shown in FIGURE 8 this escapement may consist of a pendulum 45 carrying escapement elements, for example, two small rollers 46, 47, one at each end of a cross arm 48 which extends above the run- Vway 49 at such a distance that a slug 5t), in order to pass the escapement, must lift iirst roller 46 and then roller 47, thus causing the pendulum to swing. Accordingly a column of slugs in the runway will be held up by the escapement and will be released one at a time at the rate determined by the dimensions of the pendulum.

The iirst major inspection station S (FIGURE 1) is designed to reject slugs which are over-size or which have radial projections on their periphery which may be caused by damage to the slugs. This is effected, as shown in FIGURE 9, by means of .a roller 54 conveniently having a fluted surface which may be about one inch in diameter and some two and a half inches long in the case of slugs which have a diameter f the order of one inch. This roller, which is arranged to be rotated at .about 5,000 r.p.m., is mounted above the runway 55 with its axis parallel to it and is so spaced from the runway that a normal slug 56 can pass below the roller with a few thousandths of an inch clearance. Any over-size slugs or slugs having a radially extending defect which is greater than the chosen clearance will contact the roller and will thus be thrown off the runway.

The second major inspection station 6 (FiGURE l) is designed to deal with defects numbers (l), (3), (4), and (5) above. At this station, as shown more clearly in FIGURE l0, two elongated rectangular coil systems 5S and 59 which extend in the direction of movement of a slug 6@ are arranged one above and the other below the slug as it rolls between them on runway 61. Each coil system consists of a primary winding and a secondary or pick-up winding, the primary windings 53a, 59a being connected by means of conductors 612, 63 and 64 in series and with a source of alternating voltage 65, the frequency of which may be of the order of l0 lic/second, and the pick-up windings 58h, 59h being connected by conductors 66 and 67 in the adjacent arms of a bridge network which includes equal capacitors 68 and an output terminal 69. The arrangement of the coils 53 and 59 is such that a perfect slug will pass between them with its periphery equi-distant from each coil and if, moreover, the material of which the slug is composed is homogeneous and free from random distributed 4inclusions or porosity, then the eddy currents induced at any instant at diametrically opposite parts of the periphery will be the same. Under such conditions the voltage induced in the two pick-up windings 58h, 59h will be equal and there will be no output voltage at the terminal 69 of the bridge network. Any defect in the periphery of the slug which modifies the resistance to flow of the induced eddy currents or any lack of symmetry between the slug and the two coils will cause a momentary imbalance of the bridge network, which will .then provide an output pulse at terminal 69. A `diagram of the circuit arrangement at this inspection station is shown in FIGURE 2 from which it will be seen that an output pulse from the bridge network 7 is amplied at 8 and is rectified at 9 to produce a D.C. pulse having a magnitude approximately proportional to the magnitude of the defect. This DC. pulse is fed into a trigger circuit 11i which also acts as a pulse height discriminator ensuring that defects below a certain size will not cause the slug to be rejected and Kthe output from the trigger circuit is stretched at 11 and applied -to operate a solenoid `controlled air valve 12 which, when a defective slug is present, will open to release a blast of air which causes this slug to be blown oi `the runway into a rejection chute.

A Wiring diagramy of the circuit arrangement of FIG- URE 2 is shown in FIGURE 11 wherein the selective amplier comprises valves V1, V2 and V3, the detector and pulse amplifier comprise the rectiiiers MRI and MR2 and valve V4, while the pulse height discriminator and pulse stretcher comprise valves V5 and V6. The circuit is conventional and need not Abe described in detail except lto point out that pulse height discrimination is etected by adjusting the bias, by means of potential divider P1, on the grid of valve V5.

At the next inspection station 13 (FIGURE 1), the slugs Vare tested for uniformity as regards the central hole. As shown in FIGURE l2, at this station each slug 71 is passed between two coils 14 and 14 arranged with their axes parallel with `the axis of the slug. The passage of the slug between the coils will alter the value of the mutual inductance between them and hence the `generated in one coil if the other is energised with alternating current having a frequency of, for example, kos. As shown' in FIGURE 3, the vol-tage induced in the coil 14 when a slug to be inspected passes between it and the energised coil 14 is compared with the voltage induced in a second coil 15 when a slug 17 having a hole of standard dimensions is correctly positioned between `this coil `15 and a `further coil 15 also ener-gised from the source of alternating voltage. The two coils 14 and 15 are connected as shown in a bridge circuit 18 (FIGURE 4) and the output signal obtained when the bridge is unbalanced is applied .after amplification at 19 to -a rectifier and slicer 20 which selects the significant part of the modulation envelope and controls a gate 21. In the preferred form of this larrangement the lfour coils 14, 14', 15 and 1S' which are all similar in shape, have an outside diameter which is not significantly greater than the radius of the slugs to be inspected and a ratio of inside/ outside diameter not greater than about 2:3.

The standard slug 17' is so positioned in relation to the coils 15 and 15 that its centre lies on an axis which is parallel to an `axis passing throughthe centres of the coils and which intersects the circle of the mean diameter of their windings. Irf the hole in the slug 71 (FIG- URB 12) being tested is the same size as that in the standard slug, the bridge circuit will be balanced or Iwill have a minimum output at two instants, the first .being when the centre of the slug 71 passes the point of the mean diameter circle at the leading side of the coils 14 and 14 and the second when the centre of the slug passes the point of the mean diameter circle at the trailing side of the coils, while the bridge will be unbalanced at an intermediate position of the slug when its centre is opposite the centre of the coils.

Ii, however, the slug being inspected has a hole of diameter different from that of the hole in the standard slug 17, the bridge will never balance completely and the circuit is arranged so that the slug is rejected if the second main peak in the rectified bridge signal (see Wavefor-m 20', FIGURE 4) has an amplitude which is less negative by more than a predetermined amount than the amplitude obtained when the br-idge is balanced.

While in -the ideal case a separate set of coils would be used for each diierent size of slug to be inspected, it lhas been found in practice that a single set of coils will cover a useful range of slug sizes.

The output from the bridge is `sampled at the appropriate instant of time that is, 'when the center of the slug be-ing tested passes the trailing side of the coils, by means of a pulse produced by differentiating the output of a suitably positioned photo-cell 22, FGS. 4 and 13, .as light on it is interrupted by the advancing edge of the slug to be tested. The output from the detector and slicer 20 (FIG. 4) is applied as a bias to control the gain of a valve (see valve V of FG. 13) which acts as the gate 21 and to which the sampling pulse from the photo cell 22 is applied. When the bridge is balanced, the bias will have `a maximum negative Value (see waveform 201', FIG. 4) an'd the gain of the valve twill be substantially zero. Under these conditions, therefore, the valve will not pass the sampling pulse. When, however, the bridge is unbalanced owing to -an error in hole size of a slug being tested, the bias on the Valve will become less negative and its lgain will increase in proportion to the error. Accordingly, when the bridge is unbalanced the valve will pass the sampling pulse with a height which is a measure of the extent of unbalance at that instant and hence of the error in the hole size in the slug being inspected. The sampling pulse then passes to a pulse 'height :discriminating `circuit 23 which is conveniently a monostable circuit which also amplifies and stretches the pulse, through a further pulse stretcher 24 and is then applied to operate a solenoid controlled air valve 25 which as in the previous inspection station operates to release a jet of air to blow defective slugs off the runway A wiring diagram of the electronic .apparatus of FIG- URE 4 is shown in FIGURE 13 wherein the selective amplifier comprises the valves V8 and V9, the detector comprises the rectifiers MRS and MR4, the gate comprises the valve V10, and the pulse height discriminator `and pulse stretcher the valves V11 and V12. As can' be seen the output pulse from photo-cell 22, conveniently a germaniumphoto-diode, is applied to the first grid of valve V10 while the output from rectifiers MR3` and MR4 is Iapplied to control .the lbias on the third grid of this valve and thereby the gain. Potential dividers P2 and P3 are provided for adjusting the standing bias on the first 6 and third grids of the valve V10 and hence the operating conditions of the gate.

The last inspection station consists of a further gap 26 in -the runway which will be effective to eliminate faulty slugs which may have passed the earlier inspection stations. Finally, all the slugs which pass this `gap are allowed to drop into a hopper.

It has been lfound that this apparatus may be used to inspect slugs at the rate of 250 or more a minute with a high onder of accuracy. For example it is capable of reject-ing slugs having radial protrusions of the order of 0.005 inch, lenticular defects involving a loss of material of about 5 mgms. in a total weight of 5 gms. and errors in hole size of 0.003 inch.

It will be appreciated that the apparatus specifically described may be used for inspecting other types of articles, for example ball bearings, and that for such other purposes it may be modified a-s to the number and order of the inspecting stations and as to the way in which the Iarticles to be inspected are moved past the inspecting stations. For the particular duty described, however, it is found that the specified order of the inspecting s-tations -is essential apart, however, tfrom the possibility of arranging that station 13 comes before and not after st-ation 6.

I claim:

1. Apparatus for inspecting aluminium slugs of disclike shape and having a central aperture therein, comprising lan inclined runway down which the slugs are rolled one by one, a first inspection station for removing slugs having a diameter greater than the standard diameter and comprising a rotatable member arranged with its axis of rotation extending parallel to and spaced from the runway a distance such that the periphery of said member will engage the upper edge of slugs having an over-size diameter to throw them off the runway, a second inspection station disposed downstream with respect to said iirst station for removing slugs having lenticular defects or in which the metal is non-uniform and comprising a pair of elongated coils arranged above and below the runway so as to be equidistant from the adjacent edges of standard slugs and in which voltages are induced by eddy currents set up by a magnetic field in the adjacent parts of the slug passing thereby, and means responsive to non-uniformity in the voltages induced in the two coils for removing a defective slug passing the coils at that instant, and a third inspection station disposed downstream with respect to said second station for removing slugs having non-standard apertures therein and comprising a pair of coils arranged on either side of the runway with their centres lying on an axis which is intersected by the aperture in the slug as it passes thereby, means for energising one coil with alternating current, and means responsive to a non-standard voltage induced in the other coil as a slug with a non-standard aperture crosses the said axis for removing that slug.

2. Apparatus as claimed in claim 1, in which said means for removal of the slugs from the runway at the second and third inspection stations comprise means producing an air blast released by the operation of an electrically actuated valve.

3. Apparatus for delivering circular articles of concavo-convex shape in a selected orientation which comprises an inclined runway upon which Said articles roll in succession downwardly, means adapted to be engaged by the perimeter of the concave face of an article disposed in a given orientation, means cooperating with said perimeter engaging means and providing a rollway engaged by the periphery of said article in said given orientation for rolling movement of said article along said rollway out of the path of rolling movement along said runway, and means engaging the crown portion of the convex surface of an article disposed in the opposite orientation, said rollway being disposed so that the periphery of said article of opposite orientation is free of engagement with said rollway, so that said article of opspannen posite orientation continues its rolling movement downwardly along said inclined runway.

4. Apparatus as delined in claim 3 which comprises means disposed for receiving from said rollway said article of given orientation and engaging said received article for inverting said received article from said given orientation to said opposite orientation, and means connecting said inverting means to said runway for delivering Said inverted article again to said runway.

5. Apparatus for delivering circular articles of concavo-convex shape in a selected orientation which comprises an inclined runway having a surface upon which said articles roll in succession downwardly, means providing a wall extending along said runway and providing an upwardly extending surface in angular relation to said surface of said runway for engaging the perimeter of the concave face of an article disposed in a given orientation and for engaging the crown portion of the convex surface of an article disposed in the opposite orientation, a ledge disposed in the angle between said surface of said wall and said surface of said runway and providing a rollway extending in the downstream direction from and in inclined relation to said surface of said runway for engaging the periphery of said article disposed in said given orientation for rolling movement thereof along said rollway out of the path of rolling movement along said runway, the periphery of said article of opposite orientation being free of engagement with said ledge so that said article of opposite orientation continues its rolling movement downwardly along said runway with its crown portion in engagement with said wall surface, means disposed in the downstream direction along said inclined runway with respect to said rollway for receiving from said rollway said article of given orientation and engaging said received article for inverting said received article from said given orientation to said opposite orientation, and means connecting said inverting means to said runway for returning said inverted article to said runway to continue its rolling movement therealong in said opposite orientation.

6. Apparatus for inspecting a stream of metal articles of disc-like shape comprising a runway for supporting said articles with their peripheries in engagement with said runway for rolling movement thereof transversely of the Vertical in succession in a given direction along a predetermined path defined by said runway into and out of a given location, two pick-up coils disposed at said location respectively above and below said path with the magnetic axes thereof extending generally upwardly and downwardly and generally coincident, said runway being disposed in relation to said coils so that said coils are at equal distances from the periphery of a standard article rolling in engagement with said runway along said path between said pick-up coils, means providing in said location a magnetic iield traversing said pick-up coils and extending generally upwardly and downwardly across said path so that an article being inspected rolls along said path through said eld and eddy currents set up by the magnetic iield in the parts of said article that respectively are adjacent said coils are effective for inducing in said pick-up coils voltages varying with the character of said respective parts of said article being inspected, and means responsive to differences in the voltages induced in said two coils.

7. Apparatus for inspecting metal articles of circular disc-like shape and having a central aperture therein, comprising an inclined runway down which -the articles roll one by one, a pair of coils on either side of the runway and having a common axis extending generally horizontally transversely of said runway, said runway supporting each said article in its rolling movement so that said axis is intersected by the aperture in a passing article, said runway supporting a standard article so that its aperture intersects said axis in a predetermined relation thereto means for energizing one coil with alternating current,

said energizing means and said one coil cooperating with each passing article to induce a voltage in the other coil which varies with the position of the article relative to said axis and with the size of the aperture in the article, means for measuring the deviation of said voltage from a predetermined Value, a source of light and a photocell disposed on opposite sides of the runway adjacent said coils so that the light on the photocell from the source is interrupted by each passing article as it reaches a predetermined position on the runway, control means responsive to the output of the deviation measuring means to reject non-standard articles, and gate means responsive to a signal created in the photocell by the passage of an edge of an article to connect the deviation measuring means operatively to the control means, so that for all the passing articles, the induced voltage is measured at the same position of the article relative to the coils, thereby eliminating errors due to Variation of the article position at the instant of measurement.

8. Apparatus for inspecting metal articles of circular disc-like shape and having a central aperture therein, comprising an inclined runway down which the articles are rolled one by one, an inspection station for removing articles having non-standard apertures therein and comprising a pair of coils arranged on either side of the runway with their centres lying on an axis extending generally horizontally transversely of said runway, said runway supporting each said article in its rolling movement so that said axis is intersected `by the aperture in the article as it passes said axis, said runway supporting a standard article so that its aperture intersects said axis in a predetermined relation thereto, means for energizing one coil with alternating current, and means responsive to a non-standard voltage induced in the other coil as an article with a non-standard aperture crosses the said axis for removing that article.

9. Apparatus for inspecting circular metal articles of disc-like shape, comprising an inclined runway down which the articles roll one by one, an inspection station for removing articles having lenticular defects or in which the metal is non-uniform and comprising a pair of coils arranged above and below the runway with their magnetic axes extending generally upwardly and downwardly and generally coincident, said runway being disposed in relation to said coils so that said coils are equidistant from the adjacent edges of standard articles rolling on said runway and in which coils voltages are induced by eddy currents set up by a magnetic iield in the adjacent parts of the article passing thereby, and means responsive to non-uniformity in the voltages induced in the two coils by a defective article passing the coils for removing said defective article.

10. Apparatus as dened in claim 9, in which said coils extend along the runway for a distance at least equal to one-half the circumference of said articles.

ll. Apparatus for inspecting circular metal articles having opposed concave and convex faces, comprising an inclined runway down which the articles are rolled one by one, an orienting station including means for checking the orientation of the articles with respect to said concave face being disposed toward one side or the other of said runway and means for reversing the orientation of those articles oriented with their concave faces toward a given Side of the runway so that all the articles leaving -the orienting station have their convex faces oriented toward said given side of the runway, an inspection station disposed downstream with respect to said orienting station for removing articles having lenticular defects or in which the metal is non-uniform and comprising a pair of coils disposed with their magnetic axes extending generally upwardly and downwardly and generally coincident and arranged above and below the runway so as to be equidistant from the adjacent edges of standard articles rolling on said runway and in which coils voltages are induced by eddy currents set up by a magnetic field in 9 the adjacent parts of the article passing thereby, and means responsive to non-uniformity in the voltages induced in the two coils for removing a defective article passing the coils.

12. Apparatus as dened in claim 1l, in which said orientation checking means comprises guide means at said one side of the runway and adapted to be engaged by the perimeter of the concave face of only those articles which are oriented with their concave faces toward said given side; and said orientation reversing means includes a rollway cooperating with the guide means and engaged by the periphery of only the articles oriented with their concave faces toward said given side, said rollway providing a path for movement of the articles so oriented out of the runway, and means for receiving articles moving along the rollway, inverting them and returning them to the runway.

13. Apparatus for inspecting circular metal articles of disc-like shape, comprising an inclined runway down which the articles roll one by one, an inspection station for removing articles having lenticular defects or in which the metal is non-uniform and comprising a pair of coils arranged above and below the runway so as to be equidistant from the adjacent edges of standard articles rolling on said runway and in which coils voltages are induced by eddy currents set up by a magnetic eld in the adjacent parts of the article passing thereby, means responsive to non-uniformity in the voltages induced in said two coils by a defective article passing the coils for removing said defective article, a rotatable member disposed in a location preceding said inspection station along said runway and supported for rotation thereof upon an axis offset with respect to the path of movement of said articles along said runway and so that the periphery of said rotatable member is spaced a predetermined distance from the periphery of a circular article of standard diameter when in said location, and means for effecting rotation of said rotatable member, the peripheral portion of said rotatable member as it rotates engaging an article having a diametral dimension in excess of said standard diameter by a predetermined amount for effecting removal of said article of excess diametral dimension from said runway.

14. Apparatus for inspecting circular metal articles of disc-like shape, comprising an inclined runway down which the articles roll one by one, an inspection station for removing articles having lenticular defects or in which the metal is non-uniform and comprising a pair of coils arranged above and below the runway so as to be equidistant from the adjacent edges of standard articles rolling on said runway and in which coils voltages are induced by eddy currents set up by a magnetic field in the adjacent parts of the article passing thereby, means responsive to non-uniformity in the voltages induced in said two coils by a defective article passing the coils for removing said defective article, said runway having an upper portion and a lower portion in end to end relation along said path of movement of said articles and spaced apart to provide a gap in said inclined runway, the dimension of said gap along said runway being insutcient to prevent a circular article of standard diameter from passing over said gap in the rolling movement of said article at the velocity attained in rolling oown the upper of said portions of said runway, said dimension of said gap being suificient to prevent movement thereover of an article of non-circular shape and to effect falling movement of said non-circular article through said gap.

15. Apparatus for inspecting a stream of metal articles of circular shape which comprises a runway inclined to the horizontal for supporting said articles for rolling movement thereof in succession down said runway into and out of a given location, electromagnetic means disposed adjacent said runway for developing when energized a magnetic lfield in said location across the path of rolling movement of said articles, means connected to said electromagnetic means for energizing said electromagnetic means, means responsive to electromagnetic changes that are produced by dierences in the characteristics of said metal articles rolling on said runway through said eld that are reactive upon said electromagnetic means, means connected to said responsive means and activated thereby in response to a predetermined electromagnetic change and effective upon the article producing said predetermined change for removing said article from said stream, means for delivering the articles in succession to a location adjacent the upper end of said runway, and means in said upper location providing a support for and guiding the stream of articles moving through said upper location from said delivery means to said runway, said support means providing a supporting surface having a width less than the diametral dimension of said articles such that articles having gross lenticular defects will be unbalanced upon said support and will fall therefrom.

References Cited in the le of this patent UNITED STATES PATENTS 1,008,429 Osmer Nov. 14, 1911 1,555,910 Chester Oct. 6, 1925 1,778,952 McCullough Oct. 21, 1930 1,787,096 Tarone Dec. 30, 1930 1,873,315 Dreyer Aug. 23, 1932 2,250,427 Vannucci July 22, 1941 2,285,955 Wayland June 9, 1942 2,529,081 Hughes Nov. 7, 1950 2,564,143 Alsup Aug. 14, 1951 2,577,892 Hatton Dec. 11, 1951 2,594,947 Lynch Apr. 29, 1952 2,635,747 Hughes Apr. 21, 1953 2,734,628 Schlayer Feb. 14, 1956 2,798,605 Richards July 9, 1957 2,818,975 Van Holten Jan. 7, 1958 2,949,676 Finnegan Aug. 23, 1960 2,982,402 Dion May 2, 1961 2,989,179 Woods June 20, 1961 FOREIGN PATENTS 433,664 Germany Sept. 10, 1926 

1. APPARATUS FOR INSPECTING ALUMINIUM SLUGS OF DISCLIKE SHAPE AND HAVING A CENTRAL APERTURE THEREIN, COMPRISING AN INCLINED RUNWAY DOWN WHICH THE SLUGS ARE ROLLED ONE BY ONE, A FIRST INSPECTION STATION FOR REMOVING SLUGS HAVING A DIAMETER GREATER THAN THE STANDARD DIAMETER AND COMPRISING A ROTATABLE MEMBER ARRANGED WITH ITS AXIS OF ROTATION EXTENDING PARALLEL TO AND SPACED FROM THE RUNWAY A DISTANCE SUCH THAT THE PERIPHERY OF SAID MEMBER WILL ENGAGE THE UPPER EDGE OF SLUGS HAVING AN OVER-SIZE DIAMETER TO THROW THEM OFF THE RUNWAY A SECOND INSPECTION STATION DISPOSED DOWNSTREAM WITH RESPECT TO SAID FIRST STATION FOR REMOVING SLUGS HAVING LENTICULAR DEFECTS OR IN WHICH THE METAL IS NON-UNIFORM AND COMPRISING A PAIR OF ELONGATED COILS ARRANGED ABOVE AND BELOW THE RUNWAY SO AS TO BE EQUIDISTANT FROM THE ADJACENT EDGES OF STANDARD SLUGS AND IN WHICH VOLTAGES ARE INDUCED BY EDDY CURRENT SET UP BY A MAGNETIC FIELD IN THE ADJACENT PARTS OF THE SLUG PASSING THEREBY, AND MEANS RESPONSIVE TO NON-UNIFORMITY IN THE VOLTAGES INDUCED IN THE TWO COILS FOR REMOVING A DEFECTIVE SLUG PASSING THE COILS AT THAT INSTANT, AND A THIRD INSPECTION STATION DISPOSED DOWNSTREAM WITH RESPECT TO SAID SECOND STATION FOR REMOVING SLUGS HAVING NON-STANDARD APERTURES THEREIN AND COMPRISING A PAIR OF COILS ARRANGED ON EITHER SIDE OF THE RUNWAY WITH THEIR CENTRES LYING ON AN AXIS WHICH IS INTERSECTED BY THE APERTURE IN THE SLUG AS IT PASSES THEREBY, MEANS FOR ENERGISING ONE COIL WITH ALTERNATING CURRENT, AND MEANS RESPONSIVE TO A NON-STANDARD VOLTAGE INDUCED IN THE OTHER COIL AS A SLUG WITH A NON-STANDARD APERTURE CROSSES THE SAID AXIS FOR REMOVING THAT SLUG. 